Information Notice No. 83-24: Loose Parts in the Secondary Side of Steam Generators at Pressurized Water Reactors

SSINS No.: 6835
IN 83-24
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION AND ENFORCEMENT
WASHINGTON, D.C. 20555
April 28, 1983
Information Notice No. 83-24: LOOSE PARTS IN THE SECONDARY SIDE OF
STEAM GENERATORS AT PRESSURIZED WATER
REACTORS
Addressees:
All pressurized water reactors (PWRs) holding an operating license (OL) or a
construction permit (CP).
Purpose:
This information notice is provided as a notification of a potentially
significant problem pertaining to loose parts on the secondary side of steam
generators. It is expected that recipients will review the information for
applicability to their facility. No specific action or response is required
at this time.
Description of Circumstances:
Licensees and applicants have previously been provided copies of NUREG-0909
and NUREG-0651 which describe the circumstances of the loose parts related
tube rupture events at R. E. Ginna and Prairie Island 1, respectively. As a
result of these events, the staff is evaluating the need for additional
requirements to ensure the detection and prevention of loose parts as part
of the ongoing NRC Generic Program Concerning Steam Generator Tube
Degradation and Rupture Events. In the meantime, the staff is continuing to
receive reports that loose parts and foreign objects are being found in
steam generators. These occurrences have involved both operating plants and
plants under construction. Some of the most significant of these occurrences
are described in this information notice.
During a December 20-22, 1982 inspection of steam generators at Wolf Creek,
Kansas Gas and Electric Company reported finding a 1.88-lb metal wedge (1" x
1 1/2" x 3") in the secondary side of the B steam generator and a 2.8-oz, 6"
flat file in the secondary side of the C steam generator. Additionally,
debris consisting of grit, rust, sponge particles, wire bristles, and pieces
of wood were found throughout the secondary side of the steam generators. It
was not determined whether the loose parts and debris remained after
fabrication or were introduced into the steam generators during
installation.
During visual inspections (using fiber optics) in March 1983, TVA discovered
loose material on the secondary side of the Watts Bar 1 steam generators
including nuts, bolts, a grinder wheel, and "crystalline deposits."
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IN 83-24
April 28, 1983
Page 2 of 3
On February 25, 1982, Zion 1 discovered two 30 inch steel hinges and 36
nut-bolt-washer assemblies in the channel head plenum area (primary coolant
side) of a steam generator while preparing for eddy current testing. The
hinges and fasteners were part of a cover left in the steam generator from a
previous inspection. About 1100 protruding tube ends were damaged by the
hinge preventing the passage of the eddy current probe. Extensive repairs
were required.
Five broken steam generator wrapper support bars (2" diameter by about 6"
long) were found at San Onofre 1 during a visual inspection of the secondary
side of the steam generators using a remote camera in Spring of 1982.
Several other pieces of metal fragments and other debris were found. The
visual inspection indicated no evidence of significant damage to the
peripheral tubes. Some peripheral tubes exhibited ID indications or
restrictions during eddy current testing and were plugged as a conservative
measure.
Turkey Point 4 developed primary to secondary steam generator leakage on
July 6, 1982. Using fiber optics and eddy current testing, an inspection of
the entire periphery of the tube bundle was performed. Minor tube damage and
the following foreign objects were found in the secondary side of steam
generator B: 1 check valve pin, 1 threaded rod with wingnut, 1 metal plate
1/2"x2"x6", 1 weld rod, 1 bolt for check valve pin, 1 socket, 1-5" wire, and
1 flat piece of metal 3/8"x2"x1.5". Similar objects were found on the
secondary side of steam generators A and C.
Similar discoveries were made in the secondary side of the D.C. Cook Unit 1
steam generators when they were inspected during a refueling outage in July
of 1982 except that no tube damage was detected. Objects found included a 6"
diameter ball of 1/16" wire; 2 bronze lock nuts-1" across the flats x
1/16"1/8" thick; 2-3/8" x 1-1/2" cap screws with two nuts, wired together;
metal spatter, size of a half dollar; and parts of a pocket knife consisting
of 1 piece of metal 1/2" x 1-1/8" x 1/16" and 1 piece 1/2" x 4."
Visual inspection of the secondary side of the Point Beach steam generators
in November 1982 revealed a large (6") C-clamp, a 58" long bar (1/2" x 3/8"
cross section), and other loose objects. The C-clamp was found leaning
against two tubes which showed definite signs of mechanical damage. These
tubes had developed leakage in 1978 and had been plugged.
Loose parts have been implicated in two of the four tube rupture events in
operating plants. In addition to tube ruptures, loose parts in the secondary
side of steam generators of at least two plants have resulted in tube
damage. In most cases, the loose parts have been found before sufficient
damage had occurred to cause leakage or rupture. However, the consequences
of loose parts do present some risk to public health and safety as well as
undesirable economic consequences. Therefore, it is prudent to avoid this
problem. (See also INPO SOER 82-12, "Steam Generator Tube Ruptures Caused
by Loose Parts on the Secondary Side," which contains information and
recommendations for operating plants which may be applied appropriately to
plants under construction.)
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IN 83-24
April 28, 1983
Page 3 of 3
If you have any questions regarding these matters please contact the
Regional Administrator of the appropriate NRC Regional Office or this
Office.
Edward L. Jordan, Director
Division of Emergency Preparedness
and Engineering Response
Office of Inspection and Enforcement
Technical Contact: M. S. Wegner
301-492-4511
Attachment:
List of Recently Issued IE Information Notices